This sequel to The Ruby in the Smoke and The Shadow in the North combines heart-thumping suspense, a thorough-going examination of Victorian London's underclass, a lively gang of heroes and villains and a mystery sinister enough to leave readers filled with anxiety. An unknown evildoer has made elaborate plans to steal Sally Lockhart's life away from her--by usurping her home, her business, her daughter Harriet and, finally, her sanity. Elsewhere in London, Jewish immigrants who have fled the Russian pogroms are being systematically fleeced. Daniel Goldberg, a socialist journalist, believes that the evil genius behind these brutal acts is a shadowy figure known as the Tzaddik. Rendered homeless and hounded through London's slums, Sally endures a plight that in many ways mirrors the mistreatment of the Jews. Aided by Goldberg and a handful of the city's toughest gangsters, the dauntless heroine triumphs over this malevolence. Astute readers are likely to figure out the Tzaddik's identity long before Sally does--a bit of predictability that is at odds with Pullman's otherwise tight plotting. On the whole, however, this thought-provoking romp is as rich and captivating as a modern-day Dickens novel. Ages 12-up. (Nov.)